To increase the competence of the future network, 3GPP is developing a brand new evolved network, which is also referred as an Access Network (AN) of Release 8 (R8) or later versions herein.
Under the system architecture of the current AN, that is, under the system architecture of the AN of Release 7 (R7) or earlier versions, the procedure for inter-/intra-system handover and change is substantially the same as that of R8 or later versions with the difference that, in the R7 or earlier versions, when a source Mobility Management Network Element (MMNE) transmits a Forward Relocation Request message or a Context Response message to a destination MMNE, a PDP (Packet Data Protocol) context/bearer context information of R7 or earlier versions includes IP address and Tunnel Endpoint Identity (TEID) information of a Packet Data Network Gateway (P-GW), and the destination MMNE directly transmits an Update Bearer Request message to the P-GW and receives an Update Bearer Response message from the P-GW.
The above difference is due to the following reason: in the AN of R8 or later versions, a user equipment (UE) uses two user plane gateway devices, one is a Serving-Gateway (S-GW) and the other is a P-GW. The S-GW is the user plane anchor point of the 3GPP access network, which is also referred to as the Serving-Gateway entity or the user plane anchor point corresponding to ANs of higher versions. The P-GW is the anchor point between the 3GPP access network and non-3GPP access networks, which is also referred to as Packet Data Network Gateway entity or the user plane anchor point corresponding to ANs of lower versions. Therefore, the PDP context/bearer context of the UE includes information of such two user plane anchor points, that is, information of the S-GW and P-GW, such as address and TEID of the S-GW, and address and TEID of the P-GW. However, in the AN of R7 or earlier versions, the UE uses one user plane gateway device, i.e. the Gateway GPRS Supporting Node (GGSN), which is responsible for interfacing with external networks and implementing user plane data transfer. The GGSN is the user plane anchor point between the 3GPP networks of R7 or earlier versions and is equivalent to P-GW in the architecture of an embodiment of present invention. Therefore, the PDP context/bearer context of the UE includes the information of this anchor point, i.e. the information of P-GW, such as address and TEID of the P-GW.
Thus a problem is raised, that is, when handover/changing occurs between an AN of R8 or later versions and that of R7 or earlier versions, how does the source AN correctly transmit the user plane anchor point information needed by the destination AN?
The prior art described above also has the following drawbacks: the PDP context/bearer context Information Element (IE) carried in the Forward Relocation Request or Context Response by the source AN also carries information such as Quality of Service (QoS). In the AN of R8 or later versions, when the source MMNE transmits the Forward Relocation Request or Context Response message to the destination MMNE, the format and parameters of the information, such as QoS, carried in the PDP context/bearer context is the format and parameters of the information for R8 or later versions, while the destination MMNE of R7 or earlier versions may be unable to identify such format and parameters, thus the PDP context/bearer context IE transferred by the source MMNE of R8 or later versions may not be processed.
It can be seen from the above description that, when a user hands over or changes between networks of different versions, the source AN cannot transfer information of the user.